A real body at temperature T does not emit with the black body emissive power σ·T4 but rather with some fraction, ε.

The total emittances for a variety of surfaces is given in the following table which is an extract from the slides Radiative heat transfer for the course Heat transfer by John Richard Thome (EPFL, 2008).

Symbol
$\epsilon_{\mathrm{rad}}$
Unit
-
Related
$K_{\mathrm{t}}$
Choices
MaterialType / TreatmentTemperaturenominalminmaxmedian
AluminiumPolished, 98% pure200-6000.040.060.05
Commercial sheet900.09
Heavily oxidized90-5400.30.20.330.265
BrassHighly polished2600.04
Dull plate40-2600.22
Oxidized40-2600.460.560.51
CopperHighly polished electrolyte900.02
Slightly polished to dull400.120.150.135
Black oxidized400.04
Steelpolished40-2600.070.10.085
Stainless steelafter repeated heating230-9000.50.70.6
PaintsBlack gloss400.9
White paint400.890.970.93
Lacquer400.80.950.875
Various oil paints400.920.960.94